1. Field of the Invention
The present invention relates generally to a simple tool for removing a constant velocity joint from a splined shaft. More specifically, the present invention contemplates an impact tool, that is powered by a conventional pneumatic hammer, to deliver an axially directed force of sufficient magnitude to separate a constant velocity (CV) joint from a splined shaft.
Constant velocity, or CV, joints are widely used, as in front-drive automobiles, to transmit uniform rotary motion from one shaft to another, while permitting the shafts to be disposed at varying angles. The constant velocity joints are usually located between the drive axle and the hub for mounting each front wheel of the vehicle. The constant velocity joint insures the transmittal of motive power to each of the front wheels of the vehicle.
The constant velocity joint includes a bell-shaped housing with an axially extending stub shaft. The stub shaft is operatively associated with the hub for one of the front wheels of the vehicle. The larger end of the bell-shaped housing opens outwardly and has several axially extending recesses formed therein. A trunnion with radial arms fits into the open end of the bell-shaped housing, and case hardened ball bearings fit into the channels defined between the axial recesses in the housing and the valleys between the arms of the trunnion. An annular bearing cage, with axial slots, fits between the interior of the housing and the trunnion; the ball bearings are limited in their travel by the axial slots in the bearing cage. The hub of the trunnion defines a splined receptacle that receives complementary splines on a drive shaft.
The drive shaft usually has an annular groove formed adjacent to the end of the shaft which will be inserted into the bell-shaped housing of the constant velocity joint. The drive shaft has axially extending splines adjacent to one end; such splines are complementary to the splines defined in the hub of the trunnion. A circular clip is seated in the groove, and the drive shaft is forced into engagement with the hub of the trunnion. The circular clip maintains the drive shaft and trunnion locked together, and the clip can only be overcome by the application of a considerable amount of force.
A rubberized boot extends axially from the open end of the housing and projects over the drive shaft. Grease is retained within the boot, and lubricates the connection between the drive shaft and the constant velocity joint. The connection is subjected to diverse stresses and strains, and effective lubrication is essential to the proper functioning of the constant velocity joint.
The boot, because of its exposed location on an automobile, may be punctured, may be attacked by climatic and road conditions, or may simply wear out after extended use. At such time, as a minimum, the boot must be replaced, and, in many nstances, the joint must be repaired. In order to effectuate the necessary replacement and/or repair, the drive shaft and the constant velocity joint must be disassembled. Herein lies the crux of the problem.
Presently, the drive shaft and the constant velocity joint are removed, as an assembly, from the vehicle utilizing same. The drive shaft is then clamped in a vise, and the joint is then struck, repeatedly, by heavy hammers. After several blows have been delivered, the circular clip is destroyed, and the constant velocity joint and drive shaft can be separated. The constant velocity joint can then be serviced, as needed.
After servicing, the constant velocity joint and drive shaft are re-united, and the assembly is re-mounted on the automobile. Even skilled mechanics, addressing this problem on a daily basis, may take two, or more hours, to remove the assembly, place same in a vise, and separate the constant velocity joint from the drive shaft. After repair and/or replacement, at least one-half an hour will be consumed to replace the assembly.
Furthermore, the current separation technique relies upon the brutalization of the joint with heavy hammers, and the punishment inflicted upon the joint ma well diminish its useful life. Also, unless the hammers are utilized with a considerable degree of skill, the circular clip, or similar fasteners, will resist destruction for prolonged periods of time.
One proposed solution to the time consuming, and difficult, problem of mounting, and de-mounting, splined joints for automobiles, is set forth in U.S. Pat. No. 4,936,003, granted June 26, 1990, to C. Wayne Gloe. Such patent discloses several embodiments of a special tool, such as tool [30] (FIGS. 1-4) which can be inserted into the internally splined wheel hub [16] rotatably fixed to the vehicle, and which screws onto one end of the externally splined drive shaft [14] being installed in the hub. The other end [60] of the tool mounts to a slide hammer [40]. When the slide hammer weight [46] is banged against the tool or against the oppositely located hammer stop [48], the momentum impulse is transmitted to the splined shaft to push it out of, or into, the splined wheel hub, depending upon the direction of the movement of hammer weight. The tool is capable of handling interference fit splined joints, that previously required large press forces for assembly or disassembly, as noted in column 6, lines 64, column 7, line 22.
While Gloe provides one solution to the problem of expeditiously removing a constant velocity joint from a drive shaft, Gloe relies upon a slide hammer, and accurate manipulation thereof, to separate the CV joint and drive shaft operatively associated therewith. The special tool envisioned in Gloe must be threaded into engagement with the threads on the extension of the stub shaft projecting from the constant velocity joint. Also, the splined section of the stub shaft, that is situated inboard of the threaded extension [15], should be supported by, or engaged with, the hub [16]. Also, since a threaded connection must be established between the special tool and the threaded extension of the constant velocity joint, the special tool will not be suited for use on joints with extensions of varying sizes. The joints used on different vehicles vary in size, from manufacturer to manufacturer, to further compound the problem.